Which physiological measurement is significant to monitor in a patient with an O2 saturation below 90%?

Monitoring arterial blood gases (ABGs) is crucial for patients with oxygen saturation levels below 90%. This measurement provides a comprehensive view of a patient's respiratory function and metabolic state. It assesses the partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2), along with pH levels and bicarbonate levels.

When oxygen saturation drops below 90%, there is a potential for significant hypoxemia, making it essential to evaluate the oxygenation status and the lungs' ability to exchange gases effectively. ABGs help determine the severity of respiratory compromise and guide interventions, such as supplemental oxygen or mechanical ventilation, if required.

While venous blood gases, capillary refill time, and heart rate variability can offer some information regarding a patient's condition, they do not provide the same critical insights into respiratory status and gas exchange efficiency as arterial blood gases do. This makes ABGs particularly important in managing patients experiencing decreased oxygen saturation.